In the mid-1940s, a small group of activist dentists in Wisconsin began agitating for immediate water fluoridation. Chief among them was John Frisch, a Madison dentist and prominent member of the Wisconsin State Dental Society. Frisch had been following McKay and Dean’s work closely throughout the 1930s.

In his mind, Dean’s publications had firmly established that water containing around 1ppm fluoride was both efficacious and completely safe in the fight against dental caries. Artificial fluoride, he was convinced, was no different from natural fluoride, and endless trials and experiments would merely condemn another generation of children to the pain and misery of caries. So sure was Frisch of fluoride’s safety and efficacy, that he began to add it to his home water supply so that he could monitor any changes in his children’s’ dental health.

While the Grand Rapids trial was in its infancy, Frisch and his colleagues began to promote fluoridation throughout Wisconsin. In 1947, after two years of fierce campaigning and politicking, they finally convinced city officials to fluoridate Madison’s water supply.

To allay skeptical members of the public, for whom fluoride was primarily an ingredient in rat poison, Frisch began to increasingly invoke fluoride’s “naturalness.” “The dental profession,” he declared in 1946, “is imitating nature as closely as it can.” One only had to look to Green Bay, “where people have been drinking fluorine water with sodium fluoride supplied to it by nature for over one hundred years, and no deleterious effect of any nature has occurred in that locality.”

While the Michigan trials continued, with dozens of dental researchers descending on the state to prod and probe children’s teeth for signs of caries, Frisch and his acolytes barnstormed Wisconsin, lobbying community after community to add small amounts of sodium fluoride to its water supply.

Without any long-term toxicological studies—and apparently without any qualms—water authorities complied. Frisch’s self-proclaimed goal was to have 50 communities fluoridated by 1950, a target he duly reached.

While these numbers were quite remarkable given the rising grassroots opposition to fluoridation, Frisch would not be satisfied until every citizen in America, or for that matter, the world, could enjoy the benefits of fluoride compounds in their drinking water. Thus he grew alarmed when technical problems with the fluoride injection equipment, along with concerns about adequate sodium fluoride supplies, threatened to slow the pace of adoption.

Those concerns prompted him to write to ALCOA, which produced large quantities of sodium fluoride waste as part of its production process. “The demand for this material,” he informed them, “will soon reach astronomical proportions.” If Frisch had any qualms about the “naturalness” of ALCOA’s sodium fluoride, he managed to suppress them. But it seems unlikely that he did.

By 1950, the trial in Grand Rapids was yielding very positive results. In fact, officials in Muskegon grew increasingly agitated. From their perspective, the town’s ongoing status as the control city meant their citizens’ dental health was being sacrificed on the altar of Dean’s scientific cautiousness. They would indeed begin fluoridation in 1951, thus severely compromising Dean’s 15-year study in the eyes of fluoridation skeptics.

Meanwhile, the Wisconsin fluoridationists’ most important victory occurred at the federal level.

Frisch and his colleague, Frank Bull, the State Dental Director of Wisconsin, began to lobby the PHS to endorse water fluoridation. With anti-fluoridationist influence growing—they had already defeated several fluoridation drives in Wisconsin—Frisch and Bull were concerned that by the time Dean’s Grand Rapids trial was completed, fluoridation might be politically dead.

The PHS caved in to the pressure remarkably quickly, endorsing fluoridation in June 1950 and strongly supporting the practice thereafter. The move had a cascading effect. Within months, the American Dental Association, the American Water Works Association, the American Medical Association, and a host of other high-profile government bureaus and professional bodies all gave fluoridation their stamp of approval.

For Frisch, the PHS endorsement represented a monumental victory for dental public health. For others, it also represented new economic opportunities.

In 1951, for example, the trade journal Chemical Week enthusiastically proclaimed the coming “Water Boom for Fluorides.” “The market potential,” the author gushed, “has fluoride chemical makers goggle-eyed.” In sum, “it all adds up to a nice piece of business on all sides, and many firms are cheering the USPHS and similar groups on as they plump for the increasing adoption of fluoridation.”

Fluoridation skeptics seized upon such articles as evidence of the impure motives of fluoridation advocates. ALCOA’s involvement in discovering fluoride in water—and supplying sodium fluoride to water authorities—only deepened their skepticism.

The whole fluoridation story, in fact, lent itself remarkably well to conspiracy theorizing. For example: Andrew W. Mellon, a founder of ALCOA and one of its major stockholders, was the U.S. Treasury Secretary from 1921-1932, when the PHS was still a division of the Treasury Department. It was therefore Mellon’s PHS that ordered Dean to study fluoride in the first place. Fluoride’s transmogrification from toxic waste to public health miracle, skeptics argued, suited American industry all too well.

The PHS endorsement was certainly a major public relations victory for fluoridationists. It also meant that ALCOA and other suppliers of fluoride compounds could in good conscience take advantage of a new business opportunity.

However, it by no means guaranteed the spread of fluoridation. Neither the PHS nor any other federal or state body had the power to mandate nationwide fluoridation. Instead, the decision was left up to cities and towns throughout the country. And fluoridation skeptics had more influence over local referenda than over federal or state government agencies.

Scientists and dental researchers such as Dean were flabbergasted and appalled by the array of charges hurled at them from an assortment of activists that ran the gamut from skeptical doctors and dentists to unhinged anti-communist zealots, the latter famously parodied by Stanley Kubrick in his classic 1964 film, “Dr. Strangelove,” in which a character frets over the contamination of Americans’ “precious bodily fluids.”

Continued anti-fluoridationist lobbying culminated in 1954 with the introduction of a congressional bill that threatened to outlaw fluoridation altogether. Submitted by Roy Wier, a Democrat from Minnesota, H.R. 2341 was designed “to protect the public health from the dangers of fluorination of water.” The stakes could not have been higher: had the bill passed, it would have made it illegal for any government agency at any level to introduce fluoride into its water supply.

With over two decades of crucial involvement in fluoride and dental health issues and a list of 46 scientific papers on the subject, Dean was fluoridation’s star witness at the H.R. 2341 hearings. Allaying fears that fluoridation constituted mass medication without the consent of the targeted population, Dean insisted that fluoridation was neither a treatment nor a cure for caries. Rather, “Fluorine simply prevents the decay from developing.”

“In short,” he declared in an appeal to the moral authority of nature, “fluoridation of public water supplies simulates a purely natural phenomenon—a prophylaxis which Nature has clearly outlined in those communities that are fortunate enough to have about one part per million of fluoride naturally present in the public water supply.”

Wier’s bill languished as did anti-fluoridationists’ best chance of ending the practice. Subsequently, Dean’s naturalization of water fluoridation became the standard language of government agencies, the American Dental Association, and countless water authorities throughout the U.S. and other nations that adopted it.

Far from constituting a form of alchemical sleight of hand by which industrial pollution was converted into forced mass medication, as opponents charged, proponents of fluoridation argued that adding fluoride to drinking water was merely a case of optimizing nature: a slight tweak to adjust a chemical benefit that “Nature has clearly outlined.”

The fluoride consensus developed a dozen years before the publication of Silent Spring and the rise of the modern environmental movement. By the time environmentalism started to gain political traction in the 1960s and 1970s, fluoridation enjoyed enormous support among the scientific and policy elite.

By the late 20th century, fluoride was commonly added to most toothpaste and various other dental products, while numerous foods were fumigated with fluoride chemicals. Fluoride compounds also appeared in fast food wrappers.

Despite the mid-20th century scientific consensus, fluoride skepticism did not disappear. Scientists, dentists, and medical doctors who opposed the practice continued to publish books and articles insisting that fluoridation was problematic. Paul Ehrlich expressed this concern in 1977: “The scientific evidence supporting the efficacy and safety of mass fluoridation at the generally recommended level … is not as good as it ought to be.”

Some skeptics claimed it caused various cancers or Down Syndrome. Others contended that it was likely responsible for a raft of low-level chronic conditions. For example, people suffering from mild forms of skeletal fluorosis exhibited the same symptoms as those afflicted with arthritis, and most physicians were not trained to distinguish between the two.

In addition, several high-profile experts who had previously supported fluoridation changed sides and began to oppose the practice.

By the early 21st century, even some fluoridationists became concerned that people were being exposed to too much fluoride, a fact reflected in the 2011 EPA recommendation that water authorities reduce fluoride levels from 1ppm to 0.7ppm.

Iodized salt with fluoride sold in Germany (left). Colgate, like most American toothpastes, indicates the presence of fluoride by including it as part of the name (right).

FSA, which became the most commonly used water fluoridation product from the 1970s onward, also came under renewed scrutiny.

William Hirzy, a former senior scientist at the EPA, argued that the arsenic present in FSA likely contributed annually to hundreds of cases of lung and bladder cancer. Hirzy insisted that only pharmaceutical grade sodium fluoride should be added to drinking water, a change that would prohibitively increase the cost of fluoridation.

Meanwhile claims for fluoridation’s efficacy in reducing cavities have been revised downward significantly: in the 1950s, dentists claimed it reduced caries by over 60%, while today they offer a more modest 25%. Meta studies over the past two decades suggest both figures are inflated. Moreover, rates of dental fluorosis have increased markedly in the past quarter of a century. Despite all the charges and mounting evidence, pro-fluoridationists continued to insist that fluoridation remained a safe and necessary public health measure.

A sticker on a city electrical box in Vancouver, WA from Info Wars, a right-wing media organization known for promoting conspiracy theories (left). Signs from a 2009 protest against fluoride in Australia (right).

Non-fluoridating nations such as Sweden and France have shown that it is possible to reduce dental caries without having to engage in a practice with which a substantial proportion of the population has always felt uneasy.

No doubt those countries owe a debt to people such as McKay and Dean for demonstrating a link between fluoride and dental caries. However, it is now clear that the benefits of fluoride are primarily topical. Thus fluoridated toothpaste, rather than drinking water, has in all likelihood been the greatest contributor to fighting cavities, along with improvements in diet and overall dental health.

In fact, communities that have stopped fluoridation have not experienced an increase in dental caries. Furthermore, dental health in regions which have never fluoridated their water is not significantly different from fluoridated regions. In Canada, for example, non-fluoridated British Columbians actually have fewer cavities than fluoridated Ontarians.

One result of the long-term argument is that the fluoridationists, who are understandably frustrated by the worst excesses of the anti-fluoridationists, treat fluoridation like a sacred cause to be defended at all cost. As a result, they cling to an ahistorical view that ignores the context in which fluoridation was initially promoted and the ecological and scientific changes that have occurred since.

One can accept that fluoridation was a defendable public health measure in the mid-20th century. Tooth decay was a serious problem, and it was arguably worth taking some risks in order to tackle it. However, the continued insistence among public health authorities and dentists that community water fluoridation remains essential to good dental health is incommensurate with evidence for its effectiveness, as well as downplaying the harm of fluorosis and other problems.

In all likelihood, the only significant problem that would arise from an end to fluoridation is that the Florida phosphate industry would have to find a different way—no doubt one more expensive and less convenient—to dispose of its toxic waste.

Connett, Paul, James Beck, and H. S. Micklem, The Case against Fluoride: How Hazardous Waste Ended Up in Our Drinking Water and the Bad Science and Powerful Politics That Keep It There (White River Junction, Vermont: Chelsea Green Publishing, 2010).